Glossary
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Adequate Ventilation
Definition(s)
Adequate Ventilation
Adequate ventilation is defined as ventilation (natural or artificial) that is sufficient to prevent the accumulation of significant quantities of vapor-air or gas-air mixtures in concentration above 25 % of their lower flammable (explosive) limit, LFL (LEL). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUEL
Definition(s)
UEL
upper explosive limit (UFL preferred) API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsUEL
upper explosive limit. API RP 2201, Safe Hot Tapping Practices in the Petroleum & Petrochemical Industries, Fifth Edition, July 2003 (Reaffirmed October 2010), Global StandardsNPL
Definition(s)
NPL
neutral pressure level API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Sta/ndardsWireline Work Areas
Definition(s)
Wireline Work Areas
Those areas in which wireline work is being performed on a well through a lubricator. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVolatile Flammable Liquid
Definition(s)
Volatile Flammable Liquid
A flammable liquid whose temperature is above its flash point, or a Class II combustible liquid having a vapor pressure not exceeding 276 kPa (40 psia) at 37.8 °C (100 °F) whose temperature is above its flash point. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Inadequate
Definition(s)
Ventilation, Inadequate
Ventilation that is less than adequate. See 6.3.3 of API 500 or 6.6.3 of API 505, as applicable.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global StandardsVentilation, Inadequate
Ventilation that is less than adequate. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Inadequate
The degree of ventilation (i.e. the movement and transfer of air) achieved when, under normal operating conditions, the ventilation provided does not meet the locations required criteria (e.g. less than a specified minimum number of air changes per hour). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Adequate
Definition(s)
Ventilation, Adequate
Ventilation (natural or artificial) that is sufficient to prevent the accumulation of significant quantities of vapor-air mixtures in concentrations above 25 % of their lower flammable (explosive) limit, LFL (LEL). See 6.3.2 of API 500 or 6.6.2 of API 505, as applicable.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global StandardsVentilation, Adequate
Ventilation (natural or artificial) that is sufficient to prevent the accumulation of vapor-air or gas-air mixtures in concentrations above 25 % of their lower flammable (explosive) limit, LFL (LEL). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVentilation, Adequate
The degree of ventilation (i.e. the movement and transfer of air) achieved when, under normal operating conditions, the ventilation provided meets the location’s required criteria (e.g. equal to or greater than a specified minimum number of air changes per hour). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVapor Pressure
Definition(s)
Vapor Pressure
The pressure, measured in pounds per square inch absolute (psia), exerted by a liquid, as determined by ASTM D323, Standard Method of Test for Vapor Pressure of Petroleum Products (Reid Method). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsVapor Pressure
For a given temperature, the pressure that maintains a liquid and its vapor in equilibrium. Source: IADC UBO / MPD Glossary, December 2011. Global StandardsPurged and Pressurized
Definition(s)
Purged and Pressurized
The process of (1) purging, supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level; and (2) pressurization, supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsProtected Fired Vessel
Definition(s)
Protected Fired Vessel
Any fired vessel that is provided with equipment (such as flame arresters, stack temperature shutdowns, forced draft burners with safety controls, and spark arresters) designed to eliminate the air intake and exhaust as sources of ignition. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsPipeline Transportation Facility
Definition(s)
Pipeline Transportation Facility
A facility handling the delivery of flammable or combustible petroleum liquids or flammable gases; may include pump and compressor stations, storage facilities, manifold areas, valve sites, and pipeline right-of-way areas. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsPetroleum Refinery
Definition(s)
Petroleum Refinery
A facility within which petroleum liquids or vapors are continuously processed at elevated temperatures and pressures to effect both chemical and physical changes. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsMinimum Ignition Current Ratio
Definition(s)
Minimum Ignition Current Ratio
The ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsIgnition (Autoignition) Temperature
Definition(s)
Ignition (Autoignition) Temperature
The minimum temperature required, at normal atmospheric pressure, to initiate or cause self-sustained combustion (independent of any externally heated element). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsIgnitable (Flammable) Mixture
Definition(s)
Ignitable (Flammable) Mixture
A gas-air mixture that is capable of being ignited by an open flame, electric arc or spark, or device operating at or above the ignition temperature of the gas air mixture. See flammable (explosive) limits. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsHighly Volatile Liquid
Definition(s)
Highly Volatile Liquid
A liquid whose vapor pressure exceeds 276 kilopascals (40 psia) at 37.8 °C (100 °F. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsHVL
Definition(s)
HVL
highly volatile liquid API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsGases, lighter-than-air
Definition(s)
Gases, lighter-than-air
Gases with a specific gravity less than 1.0. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsGases, Heavier-than-air
Definition(s)
Gases, Heavier-than-air
Gases with a specific gravity greater than 1.0. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsFloor Area
Definition(s)
Floor Area
The maximum area of any horizontal plane intersecting an enclosed area. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsFlammable Liquid (Class I Liquid)
Definition(s)
Flammable Liquid (Class I Liquid)
Any liquid that has a closed-cup flash point below 37.8 °C (100 °F), as determined by the test procedures and apparatus specified in NFPA 30. See 5.2. Flammable (Class I) liquids are subdivided into Classes IA, IB, and IC (reference NFPA 30. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsFlammable, Highly Volatile Liquid
Definition(s)
Flammable, Highly Volatile Liquid
See highly volatile liquid. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsFlammable (Explosive) Limits
Definition(s)
Flammable (Explosive) Limits
The lower and upper percentages by volume of concentration of gas in a gas-air mixture that will form an ignitable mixture (reference NFPA 497). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsEnclosure, Purged
Definition(s)
Enclosure, Purged
An enclosure or building supplied with clean air or an inert gas at sufficient flow and positive pressure to reduce the concentration of any flammable gases or vapors initially present to an acceptably safe level and to maintain this safe level by positive pressure with or without continuous flow (reference NFPA 496). See purged and pressurized. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsEnclosure, Explosion Proof
Definition(s)
Enclosure, Explosion Proof
An enclosure that is capable of withstanding an explosion of a specific gas or vapor within it and of preventing the subsequent ignition of a flammable gas or vapor that may surround it, and which operates at such an external temperature that a surrounding flammable gas or vapor will not be ignited. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global StandardsEnclosure, Electrical
Definition(s)
Enclosure, Electrical
The case or housing of electrical apparatus provided to prevent personnel from accidentally contacting energized parts, and/or to protect the equipment from physical damage and the environment. Also, certain enclosures serve to prevent electrical equipment from being a source of ignition of flammable mixtures outside the enclosure.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standard